First, a minor observation. Some people aren't big fans of voicing, so some might prefer an option to turn it off (I meant to mention this for Heileen 2). Of course, for the age of the game, I certainly understand if you don't do so.

Additionally, many of these suggestions are to have the written dialogue to match the oral (much like in Heileen 2). You will also find the changes will also match any grammar correction I could suggest

Obviously, you may wish to wait until I finish it (I know, a common refrain for me doing the Steam testing :D ).

Original:
Helen
It's not the first time we talk about it...you've already had enough time to ponder! I should be offended that you are still asking me for time to think...

Suggestion:
'talk' should be 'talked' to match the vocal.

Original:
Luke
You think? It was a unpredictable fight for me.

Suggestion:
'a' should be 'an' to match the audio.

Original:
Luke
I go and take a look.

Suggestion:
"I" should be "I'll" to match the audio:
I'll go and take a look.

Original:
Tom
What you found?

Suggestion:
Add 'did' before 'you' and change 'found' to find' to match the audio:
What did you find?

Original:
Tom
I go in the kitchen to eat a snack, but when I get back we can continue discussing the fight, ok?

Suggestion:
Change "I" to "I'm a". This is bad grammatically, but it will match the audio. Seriously, he says, "I'm a go in the kitchen to eat..."

Original:
Luke
Eh??? Who is there?!

Suggestion:
"Who is" should be "Who's" to match the audio:
Eh??? Who's there?!

Original:
Female Robot
Do as I said, or in five seconds your door will be smashed open?

Suggestion:
'Said' should be 'say' to match the audio.

Original:
Without replying, I push the emergence button to call the police.

Suggestion:
'emergence' should be 'emergency' to match the audio.

Original
Tom
Goonight

Suggestion:
'Goonight' should be 'Good night'. Although, Goonight does sound like a Batman event

Original:
Maybe they'll even ask me a fee for the wrong call.

Suggestion:
Add 'for' after 'me' to match the audio:
Maybe they'll even ask me for a fee for the wrong call.

Original:
Tanya
Yes, you know, I don't like to be called 'Prototype 9'...

Suggestion:
Change 'to be called' to 'being called' to match the audio:
Yes, you know, I don't like being called 'Prototype 9'...

Original:
The game now switches into interactive mode: you'll see two panel below, on the left the one showing the possible actions for the current location, and the other on the right to move into other known place.

Suggestion:
'panel' should be 'panels'. I'd also recommend removing the 'on' before 'the left'. The last part of the sentence could be tightened up as well.

It would look like this:
The game now switches into interactive mode: you'll see two panels below. The left one shows the possible actions for the current location, and the right one allows you to move to other known place

Getting back in the groove. Before I go to typos/grammar, I would make one other recommendation, one I'm sure you're bored hearing: color the last save file like your other games.

Original:
Helen
No way! We must talk, whether you want to or not. Besides...

Suggestion:
Change 'must' to 'are going to' to match the audio:
No way! We are going to talk, whether you want to or not. Besides...

Original:
I have to admit she is one of the few people who can still cook like they did in 21th century...

Suggestion:
Add 'the' before '21' and change '21th' to '21st' to match the audio:
I have to admit she is one of the few peopel who can still cook like they did in the 21st century...

Original:
Helen
You can re open them now!

Suggestion:
Put a hyphen after 're' to get:
You can re-open them now!

Original:
Luke
Helen...you are marvellous...

Suggestion:
There should only be one 'l' on 'marvellous':
Helen...you are marvelous...

Original:
Helen
Let's just say I was hoping to met you.

Suggestion:
'met' should be 'meet' to match the audio:
Let's just say I was hoping to meet you.

Original:
Helen
But last night...I made an effort to be kind to you. And you instead? Nothing! I can't believe you are still in love with me.

Suggestion:
The phrase 'And you instead' should be changed, 'And what do I get?' to match the audio (this whole sentence was off:
But last night...I made an effort to be kind to you. And what do I get? Nothing! I can't believe you are still in love with me.

Original:
Helen
And don't you dare saying so! Because I know it's not true!

Suggestion:
Change 'saying so' to 'try saying otherwise' to match the audio:
And don't you try saying otherwise! Because I know it's not true!

Original:
Helen
Eh? A policeman...what do you want?

Suggestion:
Change 'policeman' to 'policewoman' to match the audio:
Eh? A policewoman...what do you want?

Original:
Tina
I am very sorry interrupting you, but...I'd like to see your ID.

Suggestion:
Add 'for' after 'sorry' to match the audio:
I am very sorry for interrupting you, but...I'd like to see your ID.

Original
Tanya
Why you want me to stay now?

Suggestion:
Add a 'do' after 'Why' to match the audio:
Why do you want me to stay now?

Original:
Luke
I go back to the office. By the way, you have company. Two policemen are coming to check what's going on!

Suggestion:
Change the first "I" to "I'll" to match the audio:
I'll go back to the office.

Original:
Helen with her ridiculous jealousy, and Tanya that would have broken her arm over nothing.

Suggestion:
Remove 'that' to match the audio:
Helen with her ridiculous jealousy, and Tanya would have broken her arm over nothing.

Original:
Luke
Listen to me! She...fooled me! She knew I work for Nanotech, and it's for that reason she entered my home!

Suggestion:
Change 'work' to 'worked' to match the audio (and corrects the sentence as well)

Original:
I start heading back to my flat. I still don't know what exactly what Tanya wants from me, but...I understad that if I don't do what she wants, she won't go away.

Suggestion:
'understad' is a misspelling, and should be 'understand'

Original:
I'm nervous. What does she has in mind? I think she cares about me, but...what if I'm wrong?

Suggestion:
'has' should be 'have' to match the audio.

Original
Roby
Yeah, genius, and how you think to do that?

Suggestion:
To match the audio, add 'do' after 'how':
Yeah, genius, and how do you think to do that?

Original:
Luke
You're welcome. But why you want to know this information?

Suggestion:
Add 'do' after 'why' to match the audio (and makes the sentence work better):
But why do you want to know this information?

Original:
I enter the police station, dubious about what to do. The experiment led at Nanotech's Lab are illegal, so I could report them.

Suggestion:
Make 'experiment' into 'experiments' to match the audio

Original:
I try to look around to see if there's any kind of weapon I can use, or some tecnology like a nano-disassebler, it could -

Suggestion:
A couple minor typos:
'tecnology' should be 'technology' and 'disassebler' should be 'disassembler'

Original:
Luke
Why you...you changed your mind?

Suggestion:
The 'Why' should be 'What' to match the audio. I also recommend putting another elipsis after the What to make him seem a little confused by what happened
What...you...you changed your mind?

Original:
Tina
If she follows us to the police station, I'll testimony in her favour at the process.

Suggestion:
'testimony' should be 'testify' to match the audio

Original:
Tina:
In our world there's rampant corruption. Why a manager that ruins the lives of thousands people is better than a thief or even a killer?

Suggestion:
Add 'is' after 'Why', add 'of' after 'thousands' and remove the 'is' before 'better' to match the audio (and this makes it a better sentence as well):
Why is a manager that ruins the lives of thousands of people better than a thief or even a killer?

Original:
Luke:
...You see those two destroyed roboguard down there?

Suggestion:
Make 'roboguard' plural to match the audio:
...You see those two destroyed roboguards down there?

Original:
Tom
Yes, but isn't cool to spoil the fun for others! Stop predicting the future results of fights please!

Suggestion:
Add 'it' after 'but' and add 'the' before 'fights' to match the audio:
Yes, but it isn't cool to spoil the fun for others! Stop predicting the future results of the fights please!

Original:
Tina
How about...she escaped and we don't know her wereabouts.

Suggestion:
'wereabouts' should be 'whereabouts'

Original:
Tina
See? She escaped and we don't know here wereabouts.

Suggestion:
Another case where 'wereabouts' should be 'whereabouts'. You may wish to do a big copy/replace

Suggestion:
Remove 'though' to match the audio. The sentence is actually stronger this way to:
I'll show them soon enough! I'll escape to my colony on Mars, and...

Original:
It seems that Tanya has managed to his a vital point on Julia.

Suggestion:
The 'his' should be 'hit' to match the audio

Original:
No, if you have plenty of money, resources and... robot slaves at your service like Mr. Richard.

Suggestion:
'No' should be 'Not' and remove the comma (and this matches the audio:
Not if you have plenty of money, resources, and...

Original:
We go down to my garage, where my hovercar is located. It's a very good model, quick and maneuvrable.

Suggestion:
'maneuvrable' is misspelled, and should be 'maneuverable' (It was missing an e)

Original:
Richard
No! It's not possible! You can't do this to me!

Suggestion:
Change "It's" to "That's" to match the audio:
No! That's not possible! You can't do this to me!

Original:
Helen
What you mean?

Suggestion:
Add a 'do' after 'What' to match the audio to get:
What do you mean?

Original:
Helen
Listen to yourself. Richard might be ruthless, but you're making him out to be some sort of dark mafia boss with a dark unground criminal organization.

Suggestion:
'unground' is a mispelling and should be 'underground'. Additionall, 'with a dark' is actually 'of a hidden' in the audio, and would look like:
Listen to yourself. Richard might be ruthless, but your making him out to be some sort of dark mafia boss with a hidden underground criminal organization.

Original:
Helen
L-luke...

Suggestion:
The second 'l' should be capitalized since it is in front of a name:
L-Luke...

Original:
Tanya
It is dangerous, but I don't have a choice. And with Julia away, I have a better chance at getting in.

Suggestion:
Change the 'at' after 'chance' to 'of' to match the audio:
And with Julia away, I have a better chance of getting in.

Original:
Helen
And we...we could have be there with Tom too...

Suggestion:
'be' should be 'been' to match the audio:
And we...we could have been there with Tom too...

Original:
Luke
Why don't you ask Tom how he is? He's a real expert of kamasutra!

Suggestion:
There is a 'the' before 'kamasutra' in the audio:
He's a real expert of the kamasutra!

Original:
Helen
It's this interview over now?

Suggestion:
"It's" should be "Is" to match the audio:
Is this interview over now?

Original:
Helen
Tom, is a long story.

Suggestion:
Change 'is' to "it's" to match the audio:
Tom, it's a long story.

Original:
Oh well, after all, doesn't matter. I would never stay with such a girl.

Suggestion:
Add 'it' before "doesn't" to match the audio:
Oh well, after all, it doesn't matter.

Original:
Pro. Mark
J-julia!

Suggestion:
Capitalize the second 'J' in 'julia' for being a name:
J-Julia!

Original:
If he stopped the flux, Tanya would have killed everyone, overcomed by her rage.

There's been a sudden resurgence of VNs on Steam, one of the Mangagamer VNs sold 12,000 copies even. There's certainly a market for them now which would've been completely unheard of a couple of years ago.